Finite-dimensional pair coherent state engendered via the nonlinear Bose operator realization and its Wigner phase-space distributions

We theoretically analyze the photon number distribution,entanglement entropy,and Wigner phase-space distribution,considering the finite-dimensional pair coherent state(FDPCS)generated in the nonlinear Bose operator realization.Our results show that the photon number distribution is governed by the two-mode photon number sum q of the FDPCS,the entanglement of the FDPCS always increases quickly at first and then decreases slowly for any q,and the nonclassicality of the FDPCS for odd q is more stronger than that for even q.

Finite-dimensional even and odd nonlinear pair coherent states and their some nonclassical properties

In this paper a new class of finite-dimensional even and odd nonlinear pair coherent states （EONLPCSs）, which can be realized via operating the superposed evolution operators D±（τ） on the state ｜q, 0）, is constructed, then their orthonormalized property, completeness relations and some nonclassical properties are discussed. It is shown that the finite-dimensional EONLPCSs possess normalization and completeness relations. Moreover, the finite-dimensional EONLPCSs exhibit remarkably different sub-Poissonian distributions and phase probability distributions for different values of parameters q, η and ξ.

Amplitude-squared squeezing of the generalized odd-even coherent states of the anharmonic oscillator in a finite-dimensional Hilbert space

This paper discusses the properties of amplitude-squared squeezing of the generalized odd-even coherent states of anharmonic oscillator in finite-dimensional Hilbert space. It demonstrates that the generalized odd coherent states do exhibit strong amplitude-squared squeezing effects in comparison with the generalized even coherent states.

A new finite-dimensional thermal coherent state and its Wigner distribution function

This paper constructs a new type of finite-dimensional thermal coherent states （FDTCS）, which differs from the proceeding thermal coherent state in construction, as realisations of SU（2） Lie algebra. Using the technique of integration within an ordered product of operator, it investigates the orthonormality and completeness relation of the FDTCS. Based on the thermal Wigner operator in the thermal entangled state representation, the Wigner function of the FDTCS is obtained. The nonclassical properties of the FDTCS are discussed in terms of the negativity of its Wigner function.

Wigner function for the generalized excited pair coherent state

This paper introduces the generalized excited pair coherent state （GEPCS）. Using the entangled state 〈η〉 representation of Wigner operator, it obtains the Wigner function for the GEPCS. In the ρ-γ phase space, the variations of the Wigner function distributions with the parameters q, α, k and l are discussed. The tomogram of the GEPCS is calculated with the help of the Radon transform between the Wigner operator and the projection operator of the entangled state ｜η1, η2, τ1, τ2｜. The entangled states ｜η〉 and ｜η1, η2, τ1, τ2〉 provide two good representative space for studying the Wigner functions and tomograms of various two-mode correlated quantum states.

Entanglement Involved in Pair Coherent State Studied via Wigner Function Formalism

We calculate Wigner function, tomogram of the pair coherent state by using its Sehmidt decomposition in the coherent state representation. It turns out that the Wigner function can be seen as the quantum entanglement （QE） between two two-variable Hermite polynomials （TVHP） and the tomogram is further simplified as QE of two single-variable Hermite polynomials. The Husimi function of pair coherent state is also calculated.

Study of Concurrence and D-Concurrence on Two-Qubits Resulted in Pair Coherent States in Language of SU(2) Coherent States

Pair coherent state, is a state of a two-mode radiation field that is known as a state with non-gaussian wave function. In this paper, study on the pair coherent state, we notice that with superposition of two first terms of this states, one two-qubits formed. Because of the importance of two-qubits in theory of quantum entanglement, with two different measures with the title of concurrence and D-concurrence, we have studied the amount of entanglement and discussed its details. At the end, we describe these measures for pair coherent states as a function of the amplitude of the SU（2） coherent states.

增加光子对和减少光子对相干态的统计性质

引入增加光子对相干态|ζ,q;m>_a=a^(+m)|ζ,q>和减少光子对相干态|ζ,q;+-m>_b=b^m|ζ,q>,研究了这些态所描写的光场的统计性质．结果显示当在对相干态的ａ模增加光子时，两模的平均光子数均增加，亚泊松分布性质增强；当在对相干态的ｂ模取走光子时，ｂ模的平均光子数减少，而ａ模的平均光子数却增加；ｂ模的亚泊松分布性质减弱，而ａ模的亚泊松分布性质却增强．我们还计算了场模间的相关度和场模的压缩．

双相干态光场与原子依赖强度耦合过程的腔场谱

研究了依赖强度耦合双模 J-C模型的腔场谱 ,给出了激发态原子与双相干态光场双光子共振相互作用过程光谱结构的数值结果 .发现腔场谱呈现出复杂的多峰结构 .腔场谱的频率灵敏地受两模光子数差

增加光子对和减少光子对相干态的等阶Y压缩效应

通过数值计算,研究了增加光子对相干态|,ξq;m〉A=a+m|,ξq〉和减少光子对相干态|,ξq;-m〉S=bm|,ξq〉的等阶Y压缩效应.结果表明:对于增加光子对相干态a+m|,ξq〉和减少光子对相干态bm|,ξq〉,光场都存在着等阶K(=2,3,4,5…)次方Y压缩效应,但是增加a模的光子或取走b模的光子,即随着场模上光子增加(减少)数m的增大,二者的等阶K次方Y压缩效应均减弱,且有相似的曲线变化规律.

减少光子奇(偶)对相干态的非经典特性

构造了减少光子奇对相干态与减少光子偶对相干态,并用数值模拟方法研究了它们的非经典特性。结果表明,从奇对相干态与偶对相干态的第一个场模取走光子,可以显著地增强第二个场模的光子统计亚泊松分布特性;从奇对相干态的第一个场模取走光子后,在双模光子消灭算符本征值的模较小时可以增强第一个场模的光子反聚束性质。从偶对相干态的第一个场模取走光子,在双模光子消灭算符本征值的模较小时第二个场模的光子反聚束效应得到明显增强。

高QKer介质腔中对相干态场与Λ型三能级原子相互作用过程中光场的性质

本文研究了一个位于高ＱＫｅｒｒ介质腔中的Λ型三能级原子与对相干态场相互作用系统中，Ｋｅｒｒ效应对光场单模平均光子数，单模二阶相干性。

叠加激发对相干态的非经典特性(英文)

从激发对相干态出发 ,构造了叠加激发对相干态 ,研究了该叠加态的非经典特性 结果表明 :在一定条件下 ,随着相位的变化 ,叠加态场模的平均光子数呈现类似于拉比振荡的坍塌与复原现象 ,与激发对相干态相比 ,在叠加激发对相干态中亚泊松光子统计特性和Cauchy Schwatz不等式的破坏都得到了增强 。

Kerr介质中双模场与三能级原子依赖强度耦合的量子统计

研究了Kerr介质中对相干态光场与V型三能级原子依赖强度耦合相互作用的量子统计性质.对Cauchy-Schwartz不等式的研究表明:失谐量不为零(Ω1=Ω2≠0)时两模间的非经典相关程度有所增强,当初始场强ξ一定而两模场光子数差q增大时,场的非经典相关程度加强;q一定而ξ增大时,场的非经典相关程度减弱,Kerr效应使两模场的非经典相关性有所减弱.对二阶相干度的研究表明,第一模总呈现反聚束效应且Kerr效应对其影响相对较小,而第二模则聚束与反聚束效应交替出现,Kerr效应对g(222)的振荡幅度影响与q的大小有关.

基于标记配对相干态光源的测量设备无关量子密钥分配

为提升量子密钥分配的性能,基于标记配对相干态光源,提出了一种四强度诱骗态测量设备无关量子密钥分配方案。首先,利用光源的双模态特性和光子数标记技术来提升传输性能,推导了单光子对计数率下限和误码率上限的计算公式;然后,考虑统计波动,分析了数据长度有限对方案性能的影响。数值仿真结果表明:基于标记配对相干态光源的测量设备无关量子密钥分配方案在安全传输距离和密钥生成效率上都优于现有基于弱相干态光源和预报单光子源的测量设备无关量子密钥分配方案;在统计波动条件下,方案性能会随着数据长度的减少而降低,但即使数据长度减少到10^10,基于标记配对相干态光源的测量设备无关量子密钥分配方案的最大传输损耗容忍度仍可达36 dB,优于现有的其他方案。

激发对相干态的等阶Y压缩效应

用数值计算法研究了激发对相干态 |ζ ;m〉 =a+mb+m|ζ〉的等阶Y压缩效应 结果表明 :对于态a+mb+m|ζ〉 ,光场存在着等阶K(=2 ,3,4 ,5 ,… )次方Y压缩效应 ,但是随着场模上光子增加数m的增大 ,等阶K次方Y压缩效应减弱 .

增加光子奇(偶)对相干态的非经典特性

构造了增加光子奇(偶)对相干态并用数值模拟方法研究了它们的非经典性质.结果表明,增加光子奇(偶)对相干态都具有光子统计的亚泊松分布以及反聚束效应等非经典性质,是新型量子光场.在奇(偶)对相干态的两个场模上增加光子,都可以增强光场光子统计的亚泊松分布特性.

双模双光子Jaynes-Cummings模型中内在相干性的解除

给出了受Ｍｉｌｂｕｒｎ方程控制的双模双光子Ｊａｙｎｅｓ－Ｃｕｍｍｉｎｇｓ模型的精确解。由于内在消相干性的存在，原子反转以及双模光场的平均光子数随时间演化而衰减，同时光子的反聚束效应及双模光场的相干性也受到内在消相干性的影响。

叠加对相干态的相位概率分布特性

讨论了叠加对相干态的完备性关系,并根据Pegg和Barnett的相位算符和相位态的定义,计算了叠加对相干态的相位概率分布函数,并应用数值计算讨论了其特性。结果表明,叠加对相干态的相位概率分布受到相位参数和叠加参数的调制。

非简并双光子Jaynes-Cummings模型中的非经典性质研究

基于非简并双光子Jaynes-Cummings模型研究了对相干态光场的各种非经典性质,例如光场的反群聚效应,Cauchy-Schwarz不等式违背,光场的双模压缩性质等。结果表明,通过选择一定的参量或者通过选择性地探测原子内态,能使上述非经典性质得到明显增强.此外,使用(?)型三能级原子与对相干态光场作用和使用A型三能级原子与光场作用相比,各种非经典性质可以获得更佳的效果.